In order to produce bacon suitable for retail sales, pork bellies are cured by injecting or otherwise adding a salt containing fluid thereto. The purpose of curing pork bellies is to retard bacterial action and thus preserve the product. Subsequently, the cured pork bellies are transferred to a smokehouse in which the bellies remain typically for periods of four hours or more. Such smoking tends to retard fat oxidation and imbues the pork bellies with a characteristic flavor and color. Pork bellies which have been subjected to curing and smoking operations are generally referred to as bacon slabs and typically, such slabs weigh between 10-18 lbs. The bacon slabs are then cooled from the smokehouse temperature of approximately 120.degree. F. to a temperature of about 22.degree.-28.degree. F. before being inserted into a mold press. The slabs are molded into a substantially solid rectangular shape in such a press as this shape is particularly suitable for efficient slicing. The resulting bacon is sliced at a temperature of about 24.degree.-28.degree. F. and the slices are then packaged in accordance with conventional techniques for retail sale.
In order to properly cool bacon slabs so that slicing is readily facilitated, several prerequisites must be met. Initially, the cooling operation must not result in the physical impairment or deterioration of the bacon slabs such as the tearing of lean from fat tissue. In addition, weight loss of bacon slabs undergoing a cooling operation must be controlled and the cooling must be essentially uniform throughout the slabs. Uniform cooling of bacon slabs has been heretofore difficult to accomplish due to the fact that the slabs are thinner (approximately 1 inch) at one end thereof while being substantially thicker (approximately 2 inches) at the other end. Previously, satisfactory cooling has been achieved but usually only over relatively long periods (8-24 hours or greater) which increases the capital cost of cooling and storage facilities as well as the inventory of bacon in a given plant. Previous bacon preparation processes have resorted to batch type operations which require more extensive product handling and consequently higher costs.
In typical prior art bacon cooling processes, slabs are removed from the smokehouse at temperatures of approximately 120.degree. F. and are placed in refrigerated chambers to reduce the average bacon temperature to approximately 40.degree. F. over a period of up to 24 hours. Subsequently, the partially cooled bacon slabs are placed in another refrigerated chamber to further reduce the average temperature of slabs to approximately 24.degree. F., again over a relatively long period of up to 24 hours. At this point, the cooled bacon slabs may be molded for slicing. In order to substantially reduce the time necessary for cooling bacon from smokehouse temperatures to approximately 24.degree.-28.degree. F., other prior art processes have included the steps of subjecting bacon slabs removed from the smokehouse directly to intense refrigeration, preferably by direct contact with or immersion in a liquefied gas such as liquid nitrogen and permitting bacon slab temperatures to equalize at approximately 24.degree. F. Such a technique is described in U.S. Pat. No. 3,055,760. By contacting bacon slabs with liquid nitrogen which is typically supplied at a temperature of -320.degree. F., a quick-chilling of the slabs occurs and consequently, the outer layers or crust of the slab is frozen (reduced in temperature substantially below 20.degree. F.). By permitting the so-cooled bacon slabs to equilibrate for two hours or less in a zone maintained at a temperature of approximately 26.degree. F., the temperature throughout the bacon slab tends to approach this value. One serious disadvantage with the aforementioned quick cooling process is that by subjecting bacon slabs to such intense refrigeration, the freezing thereof results in a physical separation of the fat from lean bacon portions and consequently, less than desirable bacon slices are obtained from slicing operations.
Accordingly, a clear need exists for a process for preparing bacon slabs for slicing wherein the slabs are cooled from smokehouse temperatures to preferred slicing temperatures in an essentially continuous or semi-continuous manner and in a time period of approximately 2-3 hours or less without impairing the physical characteristics of the bacon slabs or the resulting appearance of sliced bacon.